Within the field of medical therapy of tumour diseases, a plurality of treatment modalities has been developed for the treatment of malignant tumour diseases: operation, cytostatic treatment, treatment with ionising radiation (gamma or particle radiation), isotope therapy and brachytherapy employing radioactive needles are examples of common treatment modalities. In spite of great progress within therapy, the tumour diseases continue to account for much human suffering, and are responsible for a high percentage of deaths in western countries. A relatively new treatment modality, photodynamic therapy, commonly abbreviated PDT, provides an interesting complement or alternative in the treatment field. A tumour-seeking agent, normally referred to as a precursor or sensitizer, is administered to the body e.g. intravenously, orally or topically. It generally accumulates in malignant tumours to a higher extent than in the surrounding healthy tissue. The tumour area is then irradiated with non-thermal red light, normally from a laser, leading to excitation of the sensitizer to a more energetic state. Through energy transfer from the activated sensitizer to the oxygen molecules of the tissue, the oxygen is transferred from its normal triplet state to the excited singlet state. Singlet oxygen is known to be particularly toxic to tissue; cells are eradicated and the tissue goes in necrosis. Because of the localisation of the sensitizer to tumour cells a unique selectivity is obtained, where surrounding healthy tissue is spared. The clinical experiences, using in particular haematoporphyrin derivative (HPD) and delta aminolevulinic acid (ALA) have shown good results.
Sensitizers may also exhibit a further useful property; when the substance is excited with visible or ultraviolet radiation, it will yield a characteristic fluorescence signal, shifted towards longer wavelengths. This signal clearly appears in contrast to the endogenous fluorescence of the tissue, which is also called autofluorescence, and is used to localise tumours and for quantifying the size of the uptake of the sensitizer in the tissue.
The limited penetration in the tissue of the activating radiation is a big drawback of PDT. The result is that only tumours less than about 5 mm thickness can be treated by surface irradiation. In order to treat thicker and/or deep-lying tumours, interstitial PDT (IPDT) can be utilised. Here, light-conducting optical fibres are brought into the tumour using, e.g. a syringe needle, in the lumen of which a fibre has been placed.
In order to achieve an efficient treatment, several fibres have been used to ascertain that all tumour cells are subjected to a sufficient dose of light so that the toxic singlet state is obtained. It has been shown to be achievable to perform dose calculations of the absorptive and scattering properties of the tissue. E.g., in the Swedish patent SE 503 408 an IPDT system is described, where six fibres are used for treatment as well as for measurement of the light flux which reaches a given fibre in the penetration through the tissue from the other fibres. In this way an improved calculation of the correct light dose can be achieved for all parts of the tumour.
According to the disclosure of SE 503 408, the light from a single laser is divided into six different parts using a beamsplitter system comprising a large number of mechanical and optical components. The light is then focused into each of the six individual treatment fibres. One fibre is used as a transmitter while the other fibres are used as receivers of radiation penetrating the tissue. For light measurement light detectors are mechanically swung into the beam path which thus is blocked, and the weak light, which originates from the fibres that collected the light which is administered to the tissue, is measured.
However, such open beam paths result in a strongly lossy beamsplitting and the resulting losses of light drastically impair the light distribution as well as the light measurement. Furthermore, such a system must often be adjusted optically, which is also an important drawback in connection with clinical treatments. The system is also large and heavy and difficult to integrate into a user-friendly apparatus. Moreover, it is difficult to control the power of the light sent into each individual fibre, which makes the measurement results unreliable.
A solution to these problems has been proposed in PCT/SE02/02050, wherein a distributor for radiation having two discs rotating relative each other is described. The radiation distributor couples optical fibres between different operation modes. For switching between several light sources to one fibre going to the patient, an assembly with a total of four discs is described. There is a need to further reduce the size of the described solution in order to further minimise the size of the system.
EP-A1-0523417 discloses a pipeline switch for distribution of radioactive emitters and/or test objects for radiotherapy, i.e. radioactive radiation treatment of a body. The emitters or test objects are conveyed within pipelines on flexible wires movable within the conduit. First pipes for conveying the flexible wires to the switch are on the one hand connected to a moveable switch element and second pipes further conveying the flexible wires to the body connected to a second, stationary switch element. The two switch elements are moveable relative each other and different constellations of pipelines are thus possible. However, when changing from one constellation to another, the flexible wire has to be retracted between each switching process, otherwise the relative movement of the switch element is obstructed. Switching times and treatment times are thus very long. Furthermore, the pipelines are not suitable for conducting radiation themselves, they just provide external protection and guidance to the flexible wires conveyed therein. The construction is also bulky and not suited for small optical fibres. Moreover, the arrangement of the disclosure is not suited for diagnosis, only for therapy, and no interactive co-operation is disclosed.
EP-A2-0280397 discloses a sterilizable endoscope having a central coherent fibre bundle for carrying an image to a viewing means. The fibre bundle is further surrounded by a large number of light fibres. The proximate end of the endoscope is provided with a coupling means for aligning the optical fibre bundle with the optical system of the viewing means and for providing an interface with light transmitting means to transmit light from a light source along the light fibres to a body cavity to be inspected. The device can be used for detection of cancer cells and treatment thereof by phototherapy. A dye is administered to the tissue being examined and subsequently exposed to an exciting laser light frequency. Cancer cells will emit fluorescent light which is detected and displayed on the video monitor and the same light frequency as this fluorescent light is then transmitted through the light fibres to the cell for phototherapy treatment. However, only the use of a single wavelength light source is disclosed, it is thus not possible to have multiple diagnostics performed without manually exchanging the light source. Moreover, it is not possible to switch between different constellations of the light fibres, i.e. all fibres always have the same function (light in or light out). The coupling means mentioned in EP-A2-0280397 is only used to adjust the path of light through a two-part endoscope when it is assembled prior to use. In addition, different fibres are used for directing therapeutic light to a cancer location and to direct diagnostic light back through the endoscope no distribution is performed between different operating modes. This solution offers for instance no neither interactive treatment nor mapping of tumours. Thus, there is a need for a new compact device allowing distributing of radiation in a system for therapy and diagnosis in a human or animal, wherein the therapy and diagnosis comprises PDT, PTT, and PDD. Moreover, a further problem to be solved by the invention is to provide an alternative solution with regard to the prior art.